Camshaft adjustment devices, in particular those which work hydraulically, are sufficiently known in the prior art. In the hydraulic camshaft adjuster there is an impeller in which vanes are integrally formed or arranged. The vanes are located in hydraulic chambers which are incorporated in an outer rotor. By way of the appropriate action of hydraulic fluid upon the respective side of the hydraulic chambers, an adjustment of the inner rotor (connected to the camshaft) in relation to the outer rotor can take place between “early abutment” and “late abutment”. In this case, the flow of hydraulic oil is controlled by an electrically activated directional valve.
In the present case, the transmission of the rotational movement of the crankshaft to the outer rotor takes place via a gearwheel, to which the outer rotor is connected fixedly in terms of rotation. In the prior art, solutions are known in which the gearwheel is designed as a chain wheel and is arranged on the outer circumference of the outer rotor or is connected fixedly in terms of rotation to the outer rotor. Examples of this are disclosed in DE 100 54 798 A1, in DE 10 2004 007 050 A1, in DE 10 2004 038 695 A1 and in DE 10 2004 062 038 A1.
The axial mounting of the camshaft in the cylinder head mostly takes place in that, first, a camshaft end is connected to the inner rotor of the camshaft adjuster by means of a central screw or by welding. The axial mounting of the inner rotor in the camshaft adjuster consequently then also ensures the axial mounting of the camshaft. The transmission of the drive torque to the outer rotor takes place by means of said gearwheel.
The gearwheel, designed as a spur wheel, presents serious disadvantages for grinding processes on account of its undercut between the end face of the gear ring and the outer end face of the sealing cover of the adjuster: if the tooth flanks are to be ground in order to achieve a sufficient toothing quality, the grinding tool rundown necessary for manufacturing purposes is no longer possible.